Process of producing artificial silk from viscose



reamed Mar. 12, less UNITED STATES PATENT OFFlCE l i, r

PRGCESS F PRODUCING ARTIFICIAL SILK FROM VISCOSE No Drawing.

Serial No. 495,289. vember 12, 1929 4 Claims.

My invention relates to a process for producing artificial silk from viscose in which strands are obtained having a more or less curled or crimped appearance. This property is of importance for certain purposes.

For the purpose of obtaining this desideratum it has already been proposed to subject artificial silk to an after-treatment in which the threads are first of all swollen by means of solutions capable of dissolving cellulose, whereupon the thread was caused to shrivel by means of other suitable liquids, and finally dried without being subjected to tension.

In contradistinctlon to this known process, the process according to my invention has the advantage that no special after-treatment is necessary, strands of artificial silk having a curled or crimped appearance being obtained by spinning in the normal manner.

2 According to my present invention a process is used therefor which is characterized by the feature that at least two bundles of filaments, which shrink to unequal extents, are united with one another.

Varieties of viscose of difierent quality (ripen-= ing, composition) may, according to my invention be spun in order to attain this purpose.

A number of spinning baths of different quality (composition, temperature, immersion length) may also be used according to my invention.

When employing the process according to my present invention at least two bundles of filaments, which have different shrinking capabilities, may be twisted together. The result is that the individual threads or filaments lie more loosely, so that the filament bundle obtains a bulky, curled appearance.

The sc-called centrifuge process, as well as bobbin spinning may be used in my new process. In the latter case, however, the strands must be dried hanging freely.

As has already been remarked, for example two or more varieties of viscose may be spun in the same spinning bath and the coagulated filaments introduced together into a spinning not. instead of varieties of viscose of different composition, e. g., different cellulose content, visccse'may also be used oi? different degrees of ripening, or two identical kinds of viscose may used, in which case certain substances are to one of the two viscoses.

Another form of the process consists t two or more difierent spinning baths wi same varieties of viscose. in this case s rung may have different com;

Application November 12, 1930,

In the Netherlands Noshow difierences in temperature, whilst different tensions also may be exerted on the two bundles oi filaments, e. g., by using unequal immersion lengths.

Further, difierent varieties of viscose and unequal immersion lengths may be used.

The following examples are given for the purpose of explaining the invention.

Two varieties of viscose, one having a salt point of 5.5 and the other a salt point of 13. are spun from difierent spinning nozzles into a normal spinning "oethcontailiing 12% of sodium sulphate, 12% of magnesium sulphateand lofhqfgulphuric (The salt point of a viscose is thoriumacid. her which gives the percentage concentration of a sodium chloride solution in which a drop of viscose Just flocculates).

The spinning is efiected in the usual manner, the two filament bundles being led into a centrifuge pot together. As a result of the difference in salt point the individual filament bundles show a very different shrinking capacity and consequently a displacement of the individual filaments with respect to one another appears in the twisted thread, which gives rise to the curled appearance of the latter.

Example II.--Two varieties of viscose are used having difierent cellulose contents, e. g., spinning solutions having a cellulose content amounting to 8% and 5% respectively. Otherwise the procedure is as given in Example I.

Example" [IL-Two spinning baths arranged side by side are used in which the same varieties of viscose are spun in the usual manner. composition of the two spinning baths may be chosen e. g. as follows:

l. 18% magnesium sulphate; 7% sodium sulphate; 1% zinc sulphate; 3% sulphuric acid.

2. 20% ammonium sulphate; 8% sulphuric acid. The filament bundles produced from these difierent spinning baths show very difierently shrinking capabilities. These two filament bundies also are led into a single spinning pot and show a curled appearance after manufacture.

it is clear that the above examples come into considertion in difierin" aspects c regards variample, instead may he f viscose of different ming baths of d erent Besides leading into smay also be comno. subsequently twistattained thereby, pro

The

vided only care is taken that the strands are dried while hanging freely.

I claim:

1. A. process of producing crepe effect composite artificial silk yarns which comprises spinning concurrently at least two bundles of artificial silk filaments, uniting the said bundles of filaments by twisting the same and effecting a difference in the shrinking characteristics of the different bundles prior to collecting the twisted composite yarn. v

2. A process according to claim 1 in which the difference in shrinking characteristics of the different bundle, is effected by spinning concurrently different varieties of cellulose solutions.

3. A process according to claim 1 in which the difference in shrinking characteristics of the different bundles is effected by employing different quality spinning baths.

4. A process according to claim 1 in which the difference in shrinking characteristics of the different bundles is efiected by subjecting the said different bundles to difierent spinning conditions 10 

